Particulate matter deposition amount estimation device, exhaust gas purification system, and particulate matter deposition amount estimation method

Abstract

There are provided calculating a differential pressure deposition amount of PM deposited in a DPF based on an exhaust gas flow rate and a differential pressure of the DPF, calculating a model deposition amount of the PM using a model in which a PM amount burned in the DPF is subtracted from the PM amount, calculating a time change rate of the differential pressure deposition amount, and setting a first coefficient to be larger than a second coefficient when the exhaust gas flow rate exceeds a predetermined value and setting the first coefficient to be small when the exhaust gas flow rate exceeds the predetermined value and the time change rate is a predetermined threshold or more when multiplying the differential pressure deposition amount and the model deposition amount by the first and second coefficients, respectively, and calculating an addition value of the respective multiplied values as the PM deposition amount.

The invention claimed is: 
     
       1. A particulate matter deposition amount estimation device comprising:
 a differential pressure deposition amount calculating unit which calculates a differential pressure deposition amount obtained by estimating a deposition amount of a particulate matter in a particulate matter removing filter removing the particulate matter from an exhaust gas of an engine based on an exhaust gas flow rate and a differential pressure between an inlet side and an outlet side of the particulate matter removing filter; 
 a model deposition amount calculating unit which calculates a model deposition amount obtained by estimating the deposition amount of the particulate matter in the particulate matter removing filter using a model in which an amount of the particulate matter burned in the particulate matter removing filter is subtracted from the amount of the particulate matter in the exhaust gas input to the particulate matter removing filter; 
 a differential pressure deposition amount change rate calculating unit which calculates a time change rate of the differential pressure deposition amount; and 
 a particulate matter deposition amount calculating unit which sets a value of a first coefficient to be larger than a value of a second coefficient when the exhaust gas flow rate exceeds a predetermined value and amends the first coefficient to be smaller than the set first coefficient when the exhaust gas flow rate exceeds the predetermined value and the time change rate of the differential pressure deposition amount exceeds a predetermined threshold value as a condition in which a sum of the first coefficient and the second coefficient becomes a constant value to calculate the deposition amount of the particulate matter, when the particulate matter deposition amount calculating unit calculates an addition value of a value obtained by multiplying the differential pressure deposition amount by the first coefficient and a value obtained by multiplying the model deposition amount by the second coefficient as the deposition amount of the particulate matter. 
 
     
     
       2. The particulate matter deposition amount estimation device according to  claim 1 ,
 wherein the particulate matter deposition amount calculating unit sets the sum of the first coefficient and the second coefficient to 1, sets the value of the first coefficient to be less than 1 when the exhaust gas flow rate exceeds the predetermined value, and sets the value of the first coefficient to 0 when the exhaust gas flow rate does not exceed the predetermined value. 
 
     
     
       3. The particulate matter deposition amount estimation device according to  claim 1 ,
 wherein the particulate matter deposition amount calculating unit decreases the set first coefficient with an increase in the time change rate of the differential pressure deposition amount when the exhaust gas flow rate exceeds the predetermined value and the time change rate of the differential pressure deposition amount is the predetermined threshold value or more. 
 
     
     
       4. The particulate matter deposition amount estimation device  claim 1 ,
 wherein the particulate matter deposition amount calculating unit outputs an instruction to perform manual forced regeneration to the particulate matter removing filter when the calculated deposition amount of the particulate matter exceeds a threshold value. 
 
     
     
       5. An exhaust gas purification system comprising:
 a particulate matter removing filter which removes a particulate matter from an exhaust gas of an engine; 
 an engine control unit which controls the engine; 
 a regeneration control unit which controls regeneration of the particulate matter removing filter; 
 a differential pressure sensor which detects a differential pressure between an inlet side and an outlet side of the particulate matter removing filter; and 
 a regeneration instruction unit which outputs an instruction to perform manual forced regeneration to the particulate matter removing filter, 
 wherein the regeneration control unit includes 
 a differential pressure deposition amount calculating unit which calculates a differential pressure deposition amount obtained by estimating a deposition amount of the particulate matter in the particulate matter removing filter based on the differential pressure and an exhaust gas flow rate input from the engine control unit, 
 a model deposition amount calculating unit which calculates a model deposition amount obtained by estimating the deposition amount of the particulate matter in the particulate matter removing filter using a model in which an amount of the particulate matter burned in the particulate matter removing filter is subtracted from the amount of the particulate matter in the exhaust gas input to the particulate matter removing filter, 
 a differential pressure change rate calculating unit which calculates a time change rate of the differential pressure deposition amount, and 
 a particulate matter deposition amount calculating unit which sets a value of a first coefficient to be larger than a value of a second coefficient when the exhaust gas flow rate exceeds a predetermined value and amends the first coefficient to be smaller than the set first coefficient when the exhaust gas flow rate exceeds the predetermined value and the time change rate of the differential pressure deposition amount exceeds a predetermined threshold value as a condition in which a sum of the first coefficient and the second coefficient becomes a constant value to calculate the deposition amount of the particulate matter, when the particulate matter deposition amount calculating unit calculates an addition value of a value obtained by multiplying the differential pressure deposition amount by the first coefficient and a value obtained by multiplying the model deposition amount by the second coefficient as the deposition amount of the particulate matter, 
 wherein the particulate matter deposition amount calculating unit outputs an instruction to perform the manual forced regeneration to the regeneration instruction unit when the calculated deposition amount of the particulate matter exceeds a threshold value. 
 
     
     
       6. The exhaust gas purification system according to  claim 5 ,
 wherein the regeneration control unit performs the manual forced regeneration through the engine control unit when receiving a manual forced regeneration performing instruction from the regeneration instruction unit. 
 
     
     
       7. A particulate matter deposition amount estimation method comprising:
 calculating a differential pressure deposition amount obtained by estimating a deposition amount of a particulate matter in a particulate matter removing filter removing the particulate matter from an exhaust gas of an engine based on an exhaust gas flow rate and a differential pressure between an inlet side and an outlet side of the particulate matter removing filter; 
 calculating a model deposition amount obtained by estimating the deposition amount of the particulate matter in the particulate matter removing filter using a model in which an amount of the particulate matter burned in the particulate matter removing filter is subtracted from the amount of the particulate matter in the exhaust gas input to the particulate matter removing filter; 
 calculating a time change rate of the differential pressure deposition amount; and 
 setting a value of a first coefficient to be larger than a value of a second coefficient when the exhaust gas flow rate exceeds a predetermined value and amending the first coefficient to be smaller than the set first coefficient when the exhaust gas flow rate exceeds the predetermined value and the time change rate of the differential pressure deposition amount exceeds a predetermined threshold value as a condition in which a sum of the first coefficient and the second coefficient becomes a constant value to calculate the deposition amount of the particulate matter, when calculating an addition value of a value obtained by multiplying the differential pressure deposition amount by the first coefficient and a value obtained by multiplying the model deposition amount by the second coefficient as the deposition amount of the particulate matter.